Long depressed by heavy debt and fears about asbestos lawsuits, shares of bottle-maker Owens-Illinois Inc. have been uncorked.

The value of stock in the Fortune 500 firm in Perrysburg has more than doubled since the start of the year and has risen 31 percent in the past three months alone.

Shares broke through the $50 threshold yesterday, closing at $50.08, up $1.64 or 3 percent, in trading on the New York Stock Exchange after a credit-rating agency upgraded its rating of the firm. The share price was more than 1 1/2 times O-I's $18.80 price at the start of 2007.

Prices are the highest since 1991 when O-I re-emerged as a public company after several years of private ownership.

" If we could tell you why the stock market moves, we'd all be retired," quipped Carol Gee, a company spokesman.

Officials of metro Toledo's second-largest corporation believe the gains can be traced to improved profits, reduced borrowing, and the success of cost-cutting moves begun in 2004, she said.

Noting O-I's improved performance, Fitch Ratings upgraded the company's credit rating yesterday to B+ from B and indicated a further upgrade is likely.

Although the rating is still four notches below investment grade in a classification assigned to "junk bonds," Fitch cited the company's "leading market positions, global footprint, technology leadership, and long-term customer relationships with large, stable customers."

The increases in O-I's shares have not gone unnoticed on Wall Street.

Ghansham Panjabi, of Wachovia Securities, said O-I shares are worth $55 to $58 each based on expected 2008 earnings.

"We believe that [the] O-I turnaround story will continue to unfold over the medium term," he said last week in a research note.

He likes the emphasis Chief Executive Officer Albert Stroucken has placed on increasing prices to breweries, wineries, and other key customers to keep pace with rising costs. Customers include the nation's largest beer and liquor manufacturers and wineries worldwide.

The analyst noted that some investors question how much higher O-I shares can go, but Mr. Panjabi predicted that they will continue to rise more rapidly than others in the packaging industry.

Richard Skidmore, of Goldman Sachs Group, rates O-I shares a "Buy." He correctly predicted last October that they would rise to $50.

Quarterly profits, he noted, have beaten Wall Street forecasts for four consecutive quarters.

"O-I is paying down another $1.2 billion of debt in the fourth quarter of 2007 as a result of stronger free cash flow and an asset sale " he wrote in a research note Oct. 25.

The payment will take O-I's debt below $4 billion.

The metro Toledo firm, with 2006 sales of $7.1 billion, made $76 million from continuing operations in the third quarter. That was up from $8 million a year earlier. The plastics sale boosted net profit to $1.2 billion in the three-month period ended Sept. 30.

O-I has paid $3 billion to settle asbestos liability suits over the past 15 years. However, officials point out that the company hasn't sold asbestos-containing products in nearly 50 years, and say the problem is gradually declining.

Analysts have credited Mr. Stroucken for improvements at the company.

In an interview this year, the new CEO expressed satisfaction with the company's rising stock price, but said: "To hang your hat on a stock price is a difficult and dangerous scenario. The stock price can be fickle "